Now that most of us have bought or played with one, what is the biggest surprise to you?

The biggest surprise to me (although not really a big deal) was the tiles rotate when you hold the Surface in portrait mode. For some reason, I thought the tiles stayed in landscape mode when you hold it in the portrait position. Maybe it's because my wp7.5 tiles don't rotate when I hold the phone in landscape mode. I thought it was really cool that the tiles rotated.

I can't say I have encountered any huge surprises yet, but there have been a few pleasant ones.

1) It was very nice that once I signed in with my Microsoft account, it picked up more of the configurations settings than I expected from my laptop running Windows 8.
2) More of the Windows 7/8 desktop functionality was carried over from x86 to ARM than I expected, including trivial stuff such as the slideshow setting for the desktop background, and more significant things such as full access to the device manager, and inclusion of the really robust Windows 8 task manager.
3) A Surface RT tablet can join a Windows 7/8 Homegroup.
4) My networked Epson printer was properly set up and configured from the start. Even Windows 8 only got that one half correct.

I stand corrected since I have now found something that is a huge surprise. The Surface RT will properly display Nikon raw nef files in both Windows Explorer and the Pictures app. This just added a level of functionality I was not expecting and will allow me to leave the laptop home when doing photography.

biggest surprise for me was how nice it holds vertically with the touch cover, just like a book

and a small negative: even though it was mentioned in the reviews, I assumed the testers were intentionally straining the device to get it to slow down, but it is sluggish at times, which is a big downer for me this early in the game. i'm sure MS is working on that, but i'm used to windows products flying at first, and then slowing down after a few weeks/months...

I connected it to a projector and ran through a 15mb deck that was very graphic and transition intensive. It displayed perfectly and PPT 2013 is simply fantastic. This was my biggest surprise. Now I just need a WebEx app and I can leave the laptop at home when I travel for work...

That it is so much like my Windows machine, honestly I didn't expect to be able to set up file sharing by just in putting my wifi key. I just tried a 2GB MP4 file that is on my main desktop and the surface played it without a hicup.

Now all we need is some wizard of a Dev to give up mkv playback.

Having a video play while doing a MS Word doc this is thing is so far ahead of my iPad that it isn't even a fair comparison.